1. Field of the Invention
The present invention relates to an apparatus for capturing and removing iron oxides contained in water in feed water and condensed water systems, that is, a feed water system and a condensed water system, in a thermoelectric power plant or other electric power plant.
2. Description of the Prior Art
Most of main machines, apparatuses and pipe lines in a thermoelectric power plant or other electric power plant are ordinarily formed of iron and steel materials, and high purity water is used as a circulation fluid and the iron concentration in the system water is controlled and maintained by a water treatment of adding a minute amount of a chemical to water for preventing corrosion of constituent materials. However, while the system water used for a long time, iron is gradually dissolved out from the iron and steel materials and is accumulated in the system water in the form of iron oxides (mainly ferromagnetic Fe.sub.3 O.sub.4 and .gamma.-Fe.sub.2 O.sub.3). These iron oxides are deposited on boiler water walls, inner surfaces of pipes, turbines, high pressure feed water heaters, feed water flow meters and various valves and cause various troubles such as (1) over-heating of pipes, (2) reduction of the turbine output, (3) overloading of pumps by increase of the pressure difference and (4) incorrect indication of flow meters. Accordingly, in order to improve the reliability of the electric power plant and increase the output thereof, it is very important to remove iron oxides from water in feed water and condensed water systems.
As means for attaining an anticorrosive effect in a drain pipe line system in a thermoelectric power plant, there have been considered (1) a method in which the pH value of water in the drain system is increased and escape of ammonia is prevented, (2) a method in which an appropriate amount of oxygen is injected in bleeder pipes, and (3) a method in which hydrogen peroxide and ammonia are injected into bleeder pipes. In connection with the method (1), ammonia injecting apparatuses have been attached to drain systems in some plants, but the effect attainable by injection of ammonia is indefinite and this method is not ordinarily adopted. The methods (2) and (3) were tried and experiments were made in German power plants, but these methods are not ordinarily adopted. Although various researches have thus been made on the method for attaining an anticorrosive effect in a drain pipe line system, a practically applicable method has not been developed and at the present, it is impossible to prevent iron from being dissolved out from drain pipe line systems. Furthermore, removal of iron oxides present in a drain pipe line system has not been examined.